Generally, a dome sheet used in a keypad for mobile phones or a membrane switch is manufactured by attaching a plurality of metal or poly domes on predetermined positions of a dome retainer film.
An electro luminescence (hereinafter, referred to as “EL”) dome sheet comprises a dome switch and an EL sheet integrally formed at the dome switch. The EL dome sheet is disposed between a printed circuit board and a keypad for illuminating the keypad without an additional light source, such as an LED.
The EL device used in the conventional EL dome sheet uses an ITO sputtered PET film (hereinafter, referred to as “ITO Film”) as a substrate. As a result, the thickness of the EL device exceeds 200 μm, which is very large. Consequently, when the EL device is folded or bent, the surface of the ITO film is damaged, and therefore, luminescence is not properly accomplished, and flexibility of the EL device is very poor.
The remainder of the EL device excluding key patterns must be cut, such that the flexibility of the EL device is considerably increased, to utilize the EL device as a keypad, which requires an additional cutting process and an additional high-temperature and high-pressure forming process for silicon molding. In addition, an FPC connecting process for providing a connector to an electric source terminal is required. As described above, several additional processes are necessary, and therefore, productivity is decreased and process difficulty is increased.